17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    // Write your code here
    if(pos==0)//lower nibble
    {
        return (reg & 0x0F);
    }
    else if(pos==1)//upper nibble
    {
        return ((reg>>4)&0x0F);
    }
    else
    {
        return 0;
    }
}

int main() {
    unsigned char reg;
    int pos;
    scanf("%hhu %d", &reg, &pos);
    printf("%d", extractNibble(reg, pos));
    return 0;
}

Use bit masking (& 0x0F) to extract the lower nibble and right-shift by 4 bits (>> 4) followed by masking to get the upper nibble.
Control the logic using pos: if pos == 0, return lower nibble; if pos == 1, return upper nibble.